The hydrogen sulfide content of some naturally-occurring gases, synthesis gases, process gases, and fuel gases produced by gasification procedures, e.g., gases produced by the gasification of coal, petroleum, shale, tar sands, etc., is often at environmentally unacceptable levels. In order to meet increasingly stringent total sulfur content requirements, effective procedures for removal of this contaminant from these "sour" gases are necessary. An additional contaminant in H.sub.2 S-containing streams in carbonyl sulfide (COS). In particular, this contaminant poses problems in conventional solvent-absorption schemes since it hydrolyzes slowly and cannot be released with the vent gas.
Where the concentrations of H.sub.2 S are high, say 5 to 50 percent by volume, the economics of H.sub.2 S removal can become critical insofar as utilization of a given process or use of a particular fuel is concerned. For example, if solvent systems are utilized to remove the H.sub.2 S, the offgases from the recovery system usually must be subjected to extensive cleanup, including incineration, in order to meet environmental requirements. On the other hand, if chemical removal, e.g., reaction of the H.sub.2 S directly with a regenerable reactant is utilized, the degradation or loss of reactant, which must be replaced, is a significant cost factor. As is evident, significant problems have existed in the purification of gas streams containing high concentrations of H.sub.2 S, and COS. The invention seeks to overcome these problems.